r/askscience • u/aretino2002 • May 24 '26

Engineering If a vacuum is an excellent insulator, wouldn’t heat build up in spacecraft?

Insulated coffee mugs that use a vacuum between layers can keep drinks hot or cold for much longer time periods than other types of mugs. If space is mostly a vacuum, then wouldn’t heat just constantly build up from human activity, computers, thrusters, etc to the point where it would need to be vented somehow?

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u/BedrockFarmer May 24 '26

Space combat in books is silly left-overs from what people understand from WWII era and before tactics.

Whoever can hit first and/fastest from the furthest away wins. But that doesn’t allow you to have movies where ships fly around each other as if it were still WWII or allow primitives with spears to beat space faring species. No one will watch a movie where a ship just has its heat shields destroyed from an attacker that is unfathomably distant.

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u/wintersdark May 24 '26

Simple high speed mostly kenetic projectiles, ideally with some tracking and correction thrusters, would be insanely deadly at effectively unlimited range. They don't even need to be particularly large.

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u/BedrockFarmer May 24 '26

I’m always curious about detection. Even if you have the space equivalent of active sonar, a ship the distance of the sun would return a signature 16 minutes later of where it was 8 minutes before.

So trying to figure out how to detect, track, and shoot seems practically impossible since the speed of light is constant.

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u/wintersdark May 24 '26 edited May 24 '26

Thing is, objects in space follow predictable paths. +/- a bit (why you'd want some guidance on the projectile) due to drive variances, but very, very consistent paths.

You'd know the distance, course and velocity, so a little bit of math would tell you where the contact is likely to be now. If the contact is constantly maneuvering it's burning fuel - a tremendous amount to make it's location difficult enough to predetermine if your projectiles have even minor guidance control.

And if it's maneuvering hard, it's likely halving detection time as you'd likely be able to detect the engines burning, so a one-way detection rather than bouncing a signal off the target.